90 Day Fiance fans first got to know Vanessa Guerra as Colt Johnson's favorite side piece.

It was not her fault that the notorious cheater was unfaithful to his wife and girlfriends, but she was involved.

Now that she's the one dating Colt, she can't shake the (realistic) fear that he'll cheat on her, too.

But Colt wants to prove that he wants her and only her -- by proposing.

In this sneak peek clip for the Sunday, May 2 episode of 90 Day: The Single Life, Colt Johnson makes his move.

“She cried when she was talking about me and how much she loves being with me,” Colt notes.

He then asks: “How could I not ask her to marry me?"

"I’m going to propose to Vanessa," Colt shares.

"I know it’s crazy," he acknowledges. "I know it’s impulsive."

"But," Colt explains, "I have to follow my heart.”

Of course, as the clip begins, they are having a different conversation.

Vanessa admits to Colt that she is afraid that he might cheat on her.

After all, Colt has been accused of cheating on, well, every ex of his that we've ever heard of.

“I’m afraid of losing you,” Vanessa confesses.

She admits: “That would crush me.”

Colt then assures her "I am satisfied" and then tells her that he loves her.

“I’m a pretty guarded person. … I don’t trust people too much," Vanessa tells the camera.

"Colt has a history of cheating and all that," she acknowledges.

"So," Vanessa explains, "that makes it even harder for me."

"I do notice I’m very vulnerable around Colt," Vanessa says.

"He’s the only person that’s been able to make me cry in years,” she reveals.

But Vanessa doesn't know what the future may bring for the two of them.

“I don’t know if we’re going to work out," Vanessa admits.

"I’m hoping for the best," she expresses.

"But," Vanessa admits, "I really don’t know.”

Colt finds an ... interesting and eyebrow-raising of explaining to Vanessa how much he loves her.

“You making me a sandwich, taking me on picnic, me eating with you," he lists.

Colt tells her "that makes me happy."

"Waking up with you every morning, holding you," he lists.

Colt then gushes: "I love you, Vanessa."

This is when he employs subterfuge.

Colt tells Vanessa that is going to walk briefly to store their picnic supplies in the car.

The plan, he says, is to meet her on the dock.

What Colt reveals to the cameras is that he is preparing to propose to Vanessa.

We just hope that Colt is going to treat her better than he treated his ex-wife.

And his ex-girlfriend, Jess Caroline. And the woman he dated after Jess.

Oh, and the woman he dated before Larissa, according to online allegations.

Maybe he will go on to cheat on Vanessa.

At this point, it's harder to imagine him not stepping out.

But maybe this famously horny leopard has changed his spots? Only time will tell.